ABSTRACT
All the researches discussed so far deal entirely with correlations between tests. In this chapter we shall be concerned Jl jL with factorial studies in which correlations are run, not between tests but between persons, or, alternatively, even within a single person from one occasion to another. The general possibilities and interrelationships of these different approaches are well illustrated by Cattell’s Covariation Chart, which is given below as Fig. 56. This diagram presents a system of rectangular co-ordinates in three dimensions, arbitrarily truncated. The co-ordinates do not represent continua, but rather a population of points arranged in serial order. Along OA lies a series of persons, a 1, a 2, etc.; along OB lies a series of personality tests, b 1, b 2, etc.; and along OC lies a series of occasions of testing, c 1, c 2, etc. —Cattell's Covariation Chart. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203753439/62ea4cd2-c6bd-44c9-88a3-83e269fe0796/content/fig_56_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
